Could anybody help me out designing "Loop stability of flyback SMPS"

Thread Starter

mishra87

Joined Jan 17, 2016
854
I have been reading so many articles and books of stability design of SMPS.
i understood some basic concepts pole, zero, RPHZ, GM, PM, GCM, PCM.
Types of compensations.

Now could anybody make me understand the cracks of loop stability.
How to choose which types of compensation to be used. ???
How to choose crossover frequency ???
How much GM and PM for a stable system ???
And how do we calculate pole and zero values.

My intention to understand all these things theoretically ????

Thank you so much in Advance !!!
 

Thread Starter

mishra87

Joined Jan 17, 2016
854
Adding further more in discussion -
Could anybody explain a bit more about below -
Its type two compensation in loop stability -
upload_2018-4-29_20-22-10.png


below is pole zero location

upload_2018-4-29_20-30-8.pngv


Now could anybody explain me below bode plot and how it define loop stability.

upload_2018-4-29_20-30-42.png




Thanks in Advance !!!
 

crutschow

Joined Mar 14, 2008
25,645
In order for the loop to be stable you need phase and gain margin (points where the phase reaches 90° and the gain reaches 0dB).
Here is some information on that.
 

Thread Starter

mishra87

Joined Jan 17, 2016
854
In order for the loop to be stable you need phase and gain margin (points where the phase reaches 90° and the gain reaches 0dB).
Here is some information on that.
Thank you so much for your reply !!!
I dont understand you mentioned "phase reaches 90 deg"

I have studied
PM- point where gain curve crosses 0 db point (from there to Phase curve distance) and that frequency is Gain cross over frequency.
GM- point where phase curve crosses -180 deg (from there to gain curve distance) and that frequency is phase cross over frequency.
 

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